Signal transduction from the biological world to physical domain, or vice versa, is a common and challenging task. For example, if in vivo neural signals can be successfully read out through an array of probes, a much better understanding of neural networks' function can be obtained (Velliste, M. et al., Nature, doi:10.1038/nature06996 (2008); Cui, X. et al., Journal of Biomedical Materials Research, 56:261-272 (2001)). Additionally, if suitable multiple control signals can be fed into neural networks, muscle motion control in disabled patients will be only one of many exciting applications (Velliste, M. et al., Nature, doi:10.1038/nature06996 (2008); Nakagawa, H. et al., Circulation, 91:2264-2273 (1995)).
The signal transduction efficiency between the biological world and engineering devices critically depends on the bio/abiotic interface. Various methods have been reported for constructing the interface to facilitate signal transductions. Functional biomolecules can be immobilized onto self-assembled monolayers (SAMs) on silicon, gold, or polymer through direct chemical bonding (Gu, F. et al., Proceedings of the National Academy of Sciences of the United States of America, 105:2586-2591 (2008); Sieval, A. B. et al., Langmuir, 14:1759-1768 (1998); Linford, M. R. et al., Journal of the American Chemical Society, 117:3145-3155 (1995); Bertilsson, L. and Liedberg, B., Langmuir, 9:141-149 (1993)) or indirect binding of biopolymers, such as streptavidin (Lahiri, J. et al., Langmuir, 15:2055-2060 (1999); Peluso, P. et al., Analytical Biochemistry, 312:113-124 (2003)) and protein G (Caruso, F. et al., Langmuir, 13:3427-3433 (1997); Bieri, C. et al., Nature Biotechnology, 17:1105-1108 (1999)). A thin film of biopolymer is commonly used to increase the affinity and stability of immobilized biomolecules (Tharanathan, R. N. and Kittur, F. S., Critical Reviews in Food Science and Nutrition, 43:61-87 (2003); Tan, W. and Desai, T. A., Biomedical Microdevices, 5:235-244 (2003)). Among these materials, conducting polymer (CP) is extensively applied as an easily fabricated and biocompatible support material for a diverse array of analytes (Cosnier, S., Analytical Letters, 40:1260-1279 (2007); Cosnier, S., Biosensors & Bioelectronics, 14:443-456 (1999); Gerard, M. et al., Biosensors & Bioelectronics, 17:345-359 (2002); Ramanavicius, A. et al., Electrochimica Acta, 51:6025-6037 (2006); Sargent, A. et al., Journal of Electroanalytical Chemistry, 470:144-156 (1999); Fan, C. H. et al., Proceedings of the National Academy of Sciences of the United States of America, 100:6297-6301 (2003)).
Currently, most of the existing CP-based biosensors incorporate biomolecular probes, such as a oligonucleotide, antibody, or enzyme, directly into the polymer film by mixing them with monomer solution immediately before electropolymerization (Wang, J. and Jiang, M., Langmuir, 16:2269-2274 (2000); Ateh, D. D. et al., Journal of the Royal Society Interface, 3:741-752 (2006); Liao, W. and Cui, X. T., Biosensors & Bioelectronics, 23:218-224 (2007)). In some cases, the addition of anionic surfactant helps to increase the immobilization efficiency, as the biomolecules will not suffer from denaturation of chemical bonding and can be immobilized through a single-step fabrication procedure. However, highly efficient immobilization for a variety of biomolecular probes requires all the parameters (i.e. voltage or current for electropolymerization and concentration of monomer and probes) to be individually optimized if any change happens.
Therefore, a universal platform for immobilizing most types of probes with high surface density and high binding activity is desirable. The present invention addresses this need and others.